1. Field of the Invention
The present invention relates to a multi-stage auto transmission for a vehicle, and more particularly, to a multi-stage auto transmission for a vehicle, which includes a gear train capable of implementing a ten-forward and one-reverse speed transmission through the same components as those in a nine-forward and one-reverse speed transmission.
2. Description of Related Art
Recently, the reinforcement of environment regulations or the increase of oil price has further required the improvement of fuel efficiency. Thus, much attention has been paid to the development of technology for improving performance in the powertrain field.
In response to the attention, a powertrain technology has been developed. The powertrain technology includes an engine downsizing technology and a multi-staging technology for an auto transmission. The engine downsizing technology has an advantage in that it can reduce the weight of a vehicle and improve fuel efficiency, and the multi-staging technology has an advantage in that it can secure operability and competitiveness in fuel efficiency. Specifically, the multi-staging technology can design an excellent transmission gear ratio in terms of power performance and fuel efficiency, using a larger number of gear shifts than a four-forward (or five-forward) and one-reverse auto transmission.
Examples of the multi-stage auto transmission include an eight-forward and one-reverse speed auto transmission implemented with a combination of three sets of planetary gears and six friction elements and a nine-forward and one-reverse speed auto transmission implemented with a combination of four sets of planetary gears, four friction elements, and two dog clutches.
In an auto transmission, however, gear shifts are implemented with a gear train to which planetary gear sets are applied. Thus, as the number of gear shifts is increased, the number of parts forming the auto transmission is also increased. Thus, in the multi-staging technology of the auto transmission, it is important to secure operability and competitiveness in fuel efficiency through a gear train structure which does not increase the number of internal parts. The increase in number of internal parts may degrade the mounting efficiency, price, weight, and power transmission efficiency of the vehicle.
Thus, an optimal structure of a gear train, which is capable of securing the maximum efficiency using a small number of parts, must be applied to develop a ten-forward and one-reverse speed auto transmission for increasing the fuel efficiency improvement effect through a larger number of gear shifts than an eight-forward and one-reverse speed auto transmission or a nine-forward and one-reverse speed auto transmission.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.